It has been suggested that certain nutritional deficiencies may alter the production of lung surfactant production in the otherwise normal adult animal. The purpose of this research is to investigate specific aspects of under- and overnutrition on lung surfactant composition and synthesis. Studies of undernutrition will utilize normal adult Wistar strain rats and overnutrition the normal and genetically obese Zucker rat. Undernutrition will include food deprivation, feeding a caloric deficient but otherwise complete diet, feeding a methyl group deficient diet and feeding a fat deficient diet. Overnutrition will include feeding the paired normal and obese Zucker rats normal diets, food deprivation, feeding a high carbohydrate, low fat diet and feeding high fat diets containing either saturated or unsaturated lipids. Animals will be normalized on AIN-76 normal diet before fasting or feeding of AIN-76 altered diets. Parameters to be determined are the lipid and protein composition of surfactant, the rate of synthesis of surfactant phospholipids, alterations in energy metabolism and the activities of key enzymes of surfactant phosphatidylocholine and phosphatidylglycerol synthesis. The isolated perfused rat lung, type II alveolar epithelial cells in primary culture, and subcellular organelles isolated from whole lung and type II cells from nutritionally codified animals will be used as models in these studies. The results of these studies will establish whether nutritional factors alter surfactant production.